ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Kinetics of the oxidation of ethyl ester of 3-oxobutyric acid by the cerium(IV) ions in relation to the Belousov-Zhabotinskii reaction

Ľ. Treindl and P. Kaplán

Department of Physical Chemistry, Faculty of Natural Sciences, Komenský University, 816 50 Bratislava

Abstract: The oxidation of ethyl ester of 3-oxobutyric acid by the Ce(IV) ions in the solution of sulfuric acid is an inner-sphere reaction, which proceeds through an intermediary complex. This reaction is a first-order reaction with respect to both reactants and is catalyzed by the H₃0⁺ ions. Its rate is inversely proportional to concentration of the HSO₄^- ions as well as of the Ce(III) ions. A plausible reaction mechanism has been proposed and the rate equation derived on the basis of this mechanism is in good agreement with the experimental equation. The activation parameters ΔH^≠  = 51.6 kJ mol^-1 and ΔS^≠ = — 53 J K^-1 mol ^-1 have been evaluated from the temperature dependen­ce of the rate constant. The modified Beiousov—Zhabotinskii reaction system containing ethyl ester of 3-oxobutyric acid as substrate is noteworthy by the fact that regular oscillations of the concentration of the Ce(IV) ions arise in an undisturbed system without any induction period even if the electrolyte is not stirred. The course of oscillations was investigated polarographically and spectrophotometrically and the corresponding activation parameters were evaluated on the basis of their dependence on temperature.

Full paper in Portable Document Format: 352a145.pdf

Chemical Papers 35 (2) 145–152 (1981)